Telephone-transmitter.



c. E. EGNER & J. G. HOLMSTRM.

TELEPHONE TRANSMITTER. APPLICATION FILED 12133.18, 1909.

Patented Nov. 2, 1909.

M/ l i Wy unirsi) STATES PATENT reifen,

CARL EMIL nenne, or STOCKHOLM, AND Jon-An' Gomma HoLi/israi/r, orserraresronNGEN, SWEDEN.

` TELEPHONE-TRANSMITTER.

'Specification of Letters Patent.-

Patented Nov. 2J, i909.

Application led February 18, 1909. Serial No. 478,684.

ject of the King of Sweden,and resident of Saltsj-Storngen, in theKingdom of Sweden, have invented certain new and useful Improvements inTelephone-Transmitters, of 1g which thefollowmg is a specification,reference being had therein to the accompanying drawing.

Y As ordinary diaphragms ammed or fixed at their edges are caused tovibrate, they vibrate in a very irregular manner substantially due tothe fact that the diaphragm is subjected to different strains atdifferent points, the diaphragm being divided into irregular iields inwhich the amplitudes of the vibrations are different. Generally thefield, in which the amplitude is greatest, is situated at some distancefrom the center of the diaphragm. This fact, evidently, is a greatdrawback in telephone-transmitters, as

the diaphragm of the transmitter, coperating with the contact-pieceslocated at the center part of the diaphragm, then does not effect thegreatest possible variations in the current. If, on the other hand, Athediaphragln is so strained, that all parts are stretched uniformly fromthe center of the diaphragm radially outward., the field with thegreatest vibrations will always be located at the center of thediaphragm, as proved bythe practice. For that reason diaphragms sostrained are very suitable for transmitters'. The straining of thediaphragm, however, is not alonesniiicient to produce the best effect.As stated above, the greatest vibrations are at the center of thediaphragm and the amplitude decreases toward the-pe riphery of the same.In transmitters consisting of carbon granules mounted in a cell insidethe diaphragm and bearing against the same, not the granules at'thecenter of the diaphragm but the granules of the cell v locatedat thegreatest distance from the center of the diaphragm will for the reasonsstated above, control the variations of the current. Consequently abetter effect will, evidently, be gained, if a second diaphragm, disk orthe like is fixed to the center of the said strained diaphragm, the saiddisk, acting upon the carbon granules of the transmitter and having thesame or substantially the same diameter as the cell of the transmitterand vibrating at all its points withthe'same amplitude as the center ofthe diaphragm.v

One form of the invention is shown in the accompanying drawing.

vFigure l is' a vertical section and Fig. l is a plan view of a`transmitter arranged in accordance with this invention. I

-l is the diaphragm and 9. is a ring shaped support for the same. Thesaid ring 2 is provided in its outer surface at the periph ery with agroove, extending around the ring and preferably tapering inward. On

- the diaphragm mounted on the ring 2 a ring 4 is mounted, provided onits inner side with a wedge shaped projection 5, which extends aroundthe ring and the shape of which corresponds to the shape of the groove3. The said ringe is fixed to the ring 2 by means of screws 6, upon thetightening of which vthe ring el forces the edge of the diaphragm intothe groove 3, the diaphragm being thus rigidly jammed between the rings2 and 4. The ring t has a suitable number of arms 7 extending inward andprovided with screwbolts 8. A frame or ring 9, preferably wedge shaped'in cross section, is mountedinsidc thering Il, and bears against thediaphragm. ',lhe'said ring 9 is acted upon by the screwbolts 8 and bytightening the said screwbolts the ring 9 is caused to force inward thepart of the diaphragm located inside the rings 2 and d. Inv this mannerthe diaphragm l is strained with substantial uniformity, from the centerradially toward the periphery, in all directions. In order that theposition of the diaphragm thus strained may be fixed, the ring Q has aplane surface l0 at its inner edge and the ring bis forced inward bymeans of the screw-bolts S. until the diaphragm bears against the saidVplane surface and assumes the posltion shown n1 Fig. 1. The said plane.surface l@ need not .necessarily extend around the whole ring 2 thecurrent in substanuany .ene saine degree,

a disk 14, preferably of carbon, is secured to i the center of thediaphragm 1, the remaining part of the said disk being free as hereinshown. The said disk is secured preferably in the following manner.After a layer of copper or any other metal hasbeen provided on one ofthe sides of the said disk Aby precipating,v a i'netal plate 15 issoldered to the' saine, provided With a screw threaded pin 16, l, whichispassed through an opening at the p center of the diaphragm 1. The saidplatel5 With the' disk 14 is then Xed by. a nut 17,

mounted outside thediaphragm 1. In order 1.

that the disk 14 may be parallel to the diaphragm 1, the disk l5 isprovided at its periphery with' a flange 18, which is nicely turnedandthe edge of which bears against the diaphragm. The disk 14 has thesaine or substantially the same diameter as the cell l] y and is incontact With-the carbon granules 12.

Owing to the said arrangement the vibrations at all points of the' disk14 have the same amplitude as the vibrations 'at 'the .center of thediaphragm l. Consequently, all granules of the cell Will assist in thesame degree in varying the current and partly in.

consequence hereof partly in consequence of the great vibrations of thedisk 14 the sound- Waves are'transmitted into variations o f the i yVcurrent inthe most effective manner.

The transmitter described above, which is adapted substantially tostrong current for 1 wireless telephoning and in Which, consequently,regard must be paid to heat gener-- ated in the'transinitter, has theadvantage ofv the diaphragm being not heated, which heat- .i 1' ingwould re'sult 1n a considerable lessening of the'effect of thetransmitter owing to the fact that the straining of thediaphragin isaffected. Owing to the heating the diaphragm would expand at its center,the

straining of the-diaphragm being thus not uniform.

Having now described our invention, what We claim as new'and desire to'secure by Letters Patent is:

In telephone transmitters especially transe i'nitters for strong currentthe combination -of a diaphragm, strained With substantial uniformityfrom its center toward its periphery, and a disk or the like, which islixed to theenter of the diaphragm and vibrates throughout substantiallyits entire area in unison With the vibrations' of that part ,of

the diaphragm to which it issecured, the

said disk forming one'of the electrodes of the transmitter,substantially as describedl presenceof tivo

